The amino acid sequence in the contraceptive polypeptide, from two cell developmental stages in the lumen of the progravid hamster oviducts, has been determined. Isolation of a protein "carrier" of the small polypeptide will continue, using blood, oviducal stroma and the two-cell developmental stages as source tissues. When the polypeptide has been synthesized and is available, we will test it first upon hamsters, then upon mice and rats. If it is not effective in mice and rats (we wxpect it will be since the large protein carrier would be species specific) then it may be necessary to attempt to isolate a similar compound from each species. We will continue two parts of the problem dealing with a potential steroid from the oviducal stroma. 1. Gross histology of oviducts and analysis for steroid dehydrogenase, and 2. extraction of oviducts and oviduct incubations to determine ability to produce steroid from appropriate precursors.